1. Field of the Invention
The present invention is directed to a lock for a motor vehicle door such as a side door lock, a rear door lock, a rear hatch lock, a hood lock or the like.
2. Description of the Prior Art
Published German Patent Application DE 196 14 122 A1 discloses a conventional motor vehicle door lock which has an electric motor for driving the actuating element. The motor vehicle door lock has worm gearing which can be rotated by a drive, an assigned worm wheel which as the actuating element bears a driving journal which can be moved along a peripheral section against spring force. The driving journal can pivot out the detent pawl of the motor vehicle door lock to release an assigned lock latch. Once the detent pawl is pivoted out, the driving journal strikes a stop on the detent pawl which blocks further motion of the driving journal. When the driving journal reaches a trailing position along the peripheral section, the drive is blocked again and thereupon shut off. Only when the detent pawl executes an overstroke motion does the stop clear the path of motion of the driving journal which then continues to move by spring force along the peripheral section into a leading position which does not limit the motion of the detent pawl. The movable support of the driving journal on the worm wheel can be regarded as a coupling between the drive and the actuating element.
In the conventional motor vehicle door lock, it is a disadvantage in that failure of the drive with the detent pawl partially pivoted out can lead to permanent blocking of the detent pawl so that it can no longer block the lock latch in the closed state. Furthermore, it is disadvantageous that the drive for the motor vehicle door lock can be used solely for actuating the detent pawl. In addition to the problem that xe2x80x9cdummyxe2x80x9d closing must be reliably prevented, in motor vehicle door locks with an electrical opening aid, there is an additional problem that occurs due to a defect in the controller. This defect results in the electric motor drive being triggered when the motor vehicle is in operation, and thus, the motor vehicle door can open while the motor vehicle is being driven.
An object of the invention is to provide a motor vehicle door lock which precludes unwanted blocking of a lock element, such as a detent pawl, even when the drive fails, and has higher functionality.
These and other objects are achieved by providing a motor vehicle door lock including a coupling which couples only when the inside handle or outside handle assigned to the motor vehicle door lock is actuated, and thus, establishes a dynamic connection between the drive and the lock element. Otherwise, the coupling remains preferably opened. Accordingly, a lock element such as a detent pawl, even with the drive failed, and regardless of the failure position of the drive or an assigned actuating element, can assume a desired position, such as blocking an assigned lock latch. As a result of the aforementioned functionality, a defect in the controller while driving which leads to unwanted starting of the drive does not lead to a malfunction, and thus, to opening of the motor vehicle door during operation of the motor vehicle. Accordingly, a door handle such as an outside handle, will not actuate and coupling and lifting of the detent pawl does not occur.
Moreover, due to the coupling, the use of the drive for other functions is enabled regardless of the motion of the actuating element or the lock element. Accordingly, a greater diversity of functions of the motor vehicle door lock is enabled. In practice, it has been found to be especially feasible to integrate the coupling into the gearing which is connected anyway to the drive and via which the actuating element can be driven. To accomplish this, the gearing is made as planetary gear system with three gear shafts, the third gear shaft of which is blocked when at least one of the inside handle and the outside handle is actuated by the control means.
Other details, features, objectives and advantages of this invention are detailed below using the drawings of one preferred embodiment.